Conversion of hydrocarbons



Patented Aug. 15, 1944 2,356,001 I CONVERSION or mznnocmons Herman Pines and Vladimir N. Ipatiefl', Chicago,

111., assignors to Universal Oil Products Company, Chicago, 11]., a corporation of Delaware No Drawing. Application August 20, 1942,

Serial No. 455,508

16 Claims.

This invention relates to a process for the conversion of hydrocarbons and more particularly to a process for converting alkyl cyclopentanes to alkyl cyclohexanes by reacting the alkyl cyclopentones with olefins in the presence of particular catalysts.

Alkyl cyclopentanes occur naturally in certain petroleum fractions and; in general, they are more reactive than the corresponding 'cyclohexane compounds. In accordance with the present invention, he alkyl cyclopentanes are converted by reactions involving simultaneous isomerization and alkylation to produce alkyl cyclohexanes.

In one specific embodiment the present invention comprises the reaction of alkyl cyclopentane hydrocarbons with olefins in the presence of an acid of phosphorus to produce alkyl cyclohexanes.

The general type of reaction which is effected by the present process is typifiedby the following equation showing the formation of l-methyl- Z-ethyl-cyclohexane from methyl cyclopentane and propylene:

The ease with which the above reaction occurs is probably due to the presence of a tertiary carbon atom'in the methyl cyclopentane molecule. Owing to the difilculty of following the character of such reactions and the invariable formation of a certain proportion of intermediate addition compounds with the organic radical and the catalyst in reactions of the present character, the above explanation is not offered as entirely adequate. It also omits mention of the formation of more highly alkylated compounds and the formation of olefin polymers, which is unavoidable to some extent in these reactions. However, under properly controlled conditions, which will be presently specified, the polymerization reactions may be kept at a minimum and the alkylationisomerization reactions may be regulated by controlling the temperature, the amount of catalyst, and the proportion of olefin to cyclopentane hydrocarbons so that maximum yields of the desired compounds will be produced.

We have found that under. the preferred conditions of the processthe product of the alkylation-isomerization reaction consists not of cyclopentane hydrocarbons but of cyclohexane hydrocarbons. In other words, isomerization occurs at the same time as the alkylation reaction. By this reaction the isomerization of alkyl cyclopentane to alkyl cyclohexane is accomplished rapidly and at a relatively low temperature. Since the simultaneous isomerization and alkylation reactions occur at lower temperatures than the straight isomerization reaction, undesirable side reactions are minimized and the reactions are more easily controlled.

Another advantage of the present process resides in theiact that nearly complete conversion of the alkyl cyclopentanes into alkyl cyclohexanes can be obtained. The cyciohexane hydrocarbons so produced may be separated from unconverted cyclopentanes and dehydrogenated catalytically or thermally to alkyl aromatic hydrocarbons, while the unconverted or incompletely converted alkyl cyclopentanes may be returned to further treatment with olefins.

The olefins which may be employed in the presentprocess may be normally gaseous and/or normally liquid. The olefin employed need not be entirely pure as any hydrocarbon fraction containing olefins may be utilized in the process. Thus a gas obtained from the cracking of oil and containing certain amounts of ethylene, propylene and butylenes may be utilized. Cyclo-olefins and polymers of normally gaseousolefins are also utilizable as alkylating agents, although they are not necessarily equivalent in their actions.

Likewise, although pure alkyl cyclopentane hydrocarbons may be used, it is within the scope of the invention to employ hydrocarbon mixtures containing alkyl cyclopentanes. A particularly suitable mixture may comprise, for example, straight run gasoline, naphtha or fractions thereof. Thus, the features of the present invention may be employed as a method of converting certain gasoline or gasoline fractions.

The invention is characterized by the use of particular catalysts, which catalysts comprise acids of phosphorus. Although the more common acids of phosphorus, such as the well known ortho phosphoric acid and also the ortho phosphorous acid, are generally preferred on account of their ready availability and low cost, it is also within the scope ofthe invention to employ any of the acids of phosphorus alone or in admixture, in so far as beneficial and economical results "are obtainable thereby. These alternative catalysts are not necessarily equivalent in their activity and the choice as to which one to employ in any particular operation will dependupon various considerations which are peculiar to any given operation. The table below lists the names, formulas, melting points, and decomposition temperatures of the acids of phosphorus.

A particularly preferred catalyst is the socalled solid phosphoric acid catalyst, which catalyst comprises a phosphoric acid supported on a solid adsorbent. Among the many adsorbents which may be satisfactorily employed, the following may be mentioned: siliceous or aluminous materials including kieselguhr, activated alumina, bauxite, fullers earth, bentonite and other selected clays, infusorial earth, and some synthetically prepared forms of silica or aluminum silicates.

The solid phosphoric acid catalysts referred to are made by mixing a phosphoric acid with a relatively inert and preferably siliceous carrier such as, for example, kieselguhr, heating at temperatures of the order of 300-400 C. to partially dehydrate the acid and fix a portion on the silica in the form of silico-phosphoric acids, grinding the cake, sizing to produce particles and rehydrating with steam at temperatures of the order of 260 C. to produce a catalyst having an acid of optimum concentration. The above procedure may be modified by extruding the original pasty mix and subjecting the extruded formed particles to the .steps of calcination and rehydration.

The molal ratio of alkyl cyclopentane hydrocarbons to olefins employed may vary considerably. It is preferable to have an excess of alkyl cyclopentanes present in'the reaction zone and usually the cyclopentanes will constitute 75 to 90% of the hydrocarbon charge, while the olefins may constitute to of the total hydrocarbons charged to the process. It is understood, however, that these percentages may vary and will depend upon the temperatures, pressures, etc. employed, aswell as upon the particular catalyst utilized.

The exact conditions of operation will depend upon the particular catalyst and hydrocarbon reactants employed. In general, the

temperature will range between about 100 C. to about 400 C. or more and will usually be within the range of about 150 C. to about 350 C. The pressures to be employed may range from about atmospheric to about .600 pounds or more and usually will be within the range of 300 to 2000 pounds.

The details of operation of the present process are comparatively simple since the cyclopentane hydrocarbons involved in the reactions are liquid at ordinary temperatures. According to the present invention, alkyl cyclopentanes are contacted with olefinichydrocarbons in the presence of the catalyst under the desired conditions of temperature and pressure until the olefin's have been substantially consumed and a substantially saturated hydrocarbon product is formed containing a relatively high proportion of alkyl cyclohexane hydrocarbons. In order to favor the alkylation reaction rather than olefin polymerization, a relatively higher molar proportion of alkyl cyclopentanes than olefins is maintained throughout the entire reaction. In some cases the molar ratio of alkyl cyclopentane to olefin may be approximately 1:1, while in other cases this ratio may be as high as 10:1 or more, the exact ratio being somewhat dependent upon the particular hydrocarbons charged. The ratio of alkyl cyclopentane to olefin hydrocarbons charged is subject to some variation and is affected considerably by 'the method of, introducing the olefin-containing fraction and the efficiency of mixing,

While the process of the present invention may be efiected either in batch or in continuous types of operation, it is usually conducted on a continuous basis, when utilizing thecatalyst in a liquid or finely divided condition, by withdrawing from the reaction zone a complex mixture of excess unreacted alkyl cyclopentanes, alkylated cyclohexanes, higher boiling hydrocarbons and catalyst, said complex mixture being withdrawn at substantially the same rate at which the hydrocarbon charging stocks and catalyst are supplied to the reaction zone. Any catalyst withdrawn from the reaction zone may be recycled thereto, all -or in part, either in admixture with some of the hydrocarbons in the form of a solution or complex, or the catalyst may be additionally separated from the hydrocarbons prior to recycling.

When employing the solid phosphoric acid catalyst, the process may be conducted by disposing the catalyst in one or more suitable re-' action zones and passing the reactants therethrough in either upward or downward flow. When desired, the alkyl cyclopentane fraction may be introduced to the inlet of the reaction zone and regulated quantities of the oleflns may be introduced at the inlet and at one or more intermediate points in the reaction zone.

Batch type operations may be employed, particularly when utilizing the acid in liquid or finely divided condition. In this type of operation the olefin fraction may be introduced into a reaction vessel containing the alkyl cyclopentanes and the catalyst. The reaction vessel is 7 preferably equipped with anefficient mixing or stirring device so as to insure intimate contact of the hydrocarbons and catalyst. Upon completion of the desired reaction the catalyst is allowed to settle and the upper hydrocarbon layer is decanted and subjected to distillation. The catalystwontaining lower layer, although apparently composed principally of addition'complexes, may frequently be reused in the process.

The following example is given to illustrate the novelty of the present invention and is not intended to unduly limit the same.

Methyl cyclopentane and propylene are contacted with a solid phosphoric acid catalyst at a temperature of 300 C. under a superatmospheric pressure of 1500 pounds. The solid phosphoric acid catalyst is prepared in accordance with the method heretofore described. The eflluent from the alkylation-isomeriz ation reaction comprises essentially unconverted methyl cyclopentane, al-

kylated cyclohexanes and some higher boiling liquid products. The eflluent is separated in one or more fractionating steps or by other means and the unconverted methyl cyclopentane is recycled to the reaction zone for further conversion therein. In addition, there will be some gaseous g I f a,aso,oo1 products, such as propane formed probably from the propylene, and these gases are and may be withdrawn from the process.

We claim as our invention:

1. A process for producing alkyl substituted cy- 4 clohexanes which comprises reacting an alkyl cyclopentane with an olefin hydrocarbon under isomerizing and allwlating conditions in the presence of an acid of phosphorus.

4. A process for producing substantial yields of alkyl substituted cyclohexanes from alkyi cyclpentanes,- which comprises reacting an alkyl cyclopentane with an olefin hydrocarbon under isomerizing and alkylating conditions in the presence of a solid catalyst comprising a mixture of phosphoric acid and a siliceous material.

5. A process for producing substantial yields of alkyl substituted cyclohexanes from alkyl cyclopentanes, which comprises reacting an alkyl cyclopentane with an olefin hydrocarbon under isomerizing and alkylating conditions in the presence of a solid catalyst comprising a mixture of phosphoric acid and kieselguhr.

6. A process for producing substantial yields of alkyl substituted cyclohexanes from aikyl cyclopentanes which comprises reacting an alkyl cyclopentane with an olefin hydrocarbon in the presence of an acid of phosphorus at a temperature between about 100 C. and about 400" C- '7. A process for producing substantial yields of alkyl substituted cyclohexanes from alkyi cyclopentanes which comprises reacting an alkyl cy- .clopentane with an olefin hydrocarbon in the 8. -A process for treating a gasoline fraction,

containing alkyl cyclopentane hydrocarbons which comprises reacting said gasoline fraction with an olefin hydrocarbon under isomerizing and alkylating conditions in the presence or an acid of phosphorus.

9. A process for treating a gasoline containing alkyl cyclopentane hydrocarbons which comprises reacting said gasoline fraction with a normally gaseous olefin hydrocarbon under isomerizing and alkylating conditions in the presence of an acid of phosphorus.

10. A process for treating a gasoline fraction containing alkyi cyclopentane hydrocarbons which comprises reacting said gasoline fraction with an olefin hydrocarbon u'nder isomerizing and alkylating conditions in the presence of a solid catalyst comprising a mixture of phosphoric acid and a siliceous material.

11. A process for producing alkyl substituted cyclohexanes which comprises subjecting an alkyl cyclopentane to simultaneous isomerization and alkylation with an olefin in the presence "of a phosphoric acid containing at least 3 hydrogen atoms per molecule.

' .12. A process for producing alkyl substituted cyclohexanes which comprises subjecting an alkyl cyclopentane to simultaneous isomerization and alkylation with an olefin in the presence or orthophosphoric acid. v

13. A process .for producing alkyl substituted cyclohexanes which comprises subjecting an al- 'hi cyclopentane-to simultaneous isomerization and alkylati on with an olefin in the presence of pyrophosphoric acid. A

HfThe process as defined im claim 'fi further characterized in that said acid is a phosphoric acid containing at least 3 hydrogen atoms per molecule.

15. The process as defined in claim 6 further characterized in that said acid is orthophosphoric presence of an acid of phosphorus at atemperature between about C. and about 350 C.

acid.

16. The process as defined in claim 6 further characterized in that said acid is pyrophosphoric acid.

HERMAN PINES. VLADIMIR N. IPA'I'IEFF.

fraction 

